// Copyright 2006-2008 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <iomanip>

#include "include/libplatform/libplatform.h"
#include "src/assembler-arch.h"
#include "src/base/platform/platform.h"
#include "src/flags.h"
#include "src/msan.h"
#include "src/snapshot/embedded-file-writer.h"
#include "src/snapshot/natives.h"
#include "src/snapshot/partial-serializer.h"
#include "src/snapshot/snapshot.h"
#include "src/snapshot/startup-serializer.h"
#include "src/source-position-table.h"

namespace {

class SnapshotFileWriter {
public:
    void SetSnapshotFile(const char* snapshot_cpp_file)
    {
        snapshot_cpp_path_ = snapshot_cpp_file;
    }

    void SetStartupBlobFile(const char* snapshot_blob_file)
    {
        snapshot_blob_path_ = snapshot_blob_file;
    }

    void WriteSnapshot(v8::StartupData blob) const
    {
        // TODO(crbug/633159): if we crash before the files have been fully created,
        // we end up with a corrupted snapshot file. The build step would succeed,
        // but the build target is unusable. Ideally we would write out temporary
        // files and only move them to the final destination as last step.
        i::Vector<const i::byte> blob_vector(
            reinterpret_cast<const i::byte*>(blob.data), blob.raw_size);
        MaybeWriteSnapshotFile(blob_vector);
        MaybeWriteStartupBlob(blob_vector);
    }

private:
    void MaybeWriteStartupBlob(const i::Vector<const i::byte>& blob) const
    {
        if (!snapshot_blob_path_)
            return;

        FILE* fp = GetFileDescriptorOrDie(snapshot_blob_path_);
        size_t written = fwrite(blob.begin(), 1, blob.length(), fp);
        fclose(fp);
        if (written != static_cast<size_t>(blob.length())) {
            i::PrintF("Writing snapshot file failed.. Aborting.\n");
            remove(snapshot_blob_path_);
            exit(1);
        }
    }

    void MaybeWriteSnapshotFile(const i::Vector<const i::byte>& blob) const
    {
        if (!snapshot_cpp_path_)
            return;

        FILE* fp = GetFileDescriptorOrDie(snapshot_cpp_path_);

        WriteSnapshotFilePrefix(fp);
        WriteSnapshotFileData(fp, blob);
        WriteSnapshotFileSuffix(fp);

        fclose(fp);
    }

    static void WriteSnapshotFilePrefix(FILE* fp)
    {
        fprintf(fp, "// Autogenerated snapshot file. Do not edit.\n\n");
        fprintf(fp, "#include \"src/v8.h\"\n");
        fprintf(fp, "#include \"src/base/platform/platform.h\"\n\n");
        fprintf(fp, "#include \"src/snapshot/snapshot.h\"\n\n");
        fprintf(fp, "namespace v8 {\n");
        fprintf(fp, "namespace internal {\n\n");
    }

    static void WriteSnapshotFileSuffix(FILE* fp)
    {
        fprintf(fp, "const v8::StartupData* Snapshot::DefaultSnapshotBlob() {\n");
        fprintf(fp, "  return &blob;\n");
        fprintf(fp, "}\n\n");
        fprintf(fp, "}  // namespace internal\n");
        fprintf(fp, "}  // namespace v8\n");
    }

    static void WriteSnapshotFileData(FILE* fp,
        const i::Vector<const i::byte>& blob)
    {
        fprintf(fp, "static const byte blob_data[] = {\n");
        WriteBinaryContentsAsCArray(fp, blob);
        fprintf(fp, "};\n");
        fprintf(fp, "static const int blob_size = %d;\n", blob.length());
        fprintf(fp, "static const v8::StartupData blob =\n");
        fprintf(fp, "{ (const char*) blob_data, blob_size };\n");
    }

    static void WriteBinaryContentsAsCArray(
        FILE* fp, const i::Vector<const i::byte>& blob)
    {
        for (int i = 0; i < blob.length(); i++) {
            if ((i & 0x1F) == 0x1F)
                fprintf(fp, "\n");
            if (i > 0)
                fprintf(fp, ",");
            fprintf(fp, "%u", static_cast<unsigned char>(blob.at(i)));
        }
        fprintf(fp, "\n");
    }

    static FILE* GetFileDescriptorOrDie(const char* filename)
    {
        FILE* fp = v8::base::OS::FOpen(filename, "wb");
        if (fp == nullptr) {
            i::PrintF("Unable to open file \"%s\" for writing.\n", filename);
            exit(1);
        }
        return fp;
    }

    const char* snapshot_cpp_path_ = nullptr;
    const char* snapshot_blob_path_ = nullptr;
};

char* GetExtraCode(char* filename, const char* description)
{
    if (filename == nullptr || strlen(filename) == 0)
        return nullptr;
    ::printf("Loading script for %s: %s\n", description, filename);
    FILE* file = v8::base::OS::FOpen(filename, "rb");
    if (file == nullptr) {
        fprintf(stderr, "Failed to open '%s': errno %d\n", filename, errno);
        exit(1);
    }
    fseek(file, 0, SEEK_END);
    size_t size = ftell(file);
    rewind(file);
    char* chars = new char[size + 1];
    chars[size] = '\0';
    for (size_t i = 0; i < size;) {
        size_t read = fread(&chars[i], 1, size - i, file);
        if (ferror(file)) {
            fprintf(stderr, "Failed to read '%s': errno %d\n", filename, errno);
            exit(1);
        }
        i += read;
    }
    fclose(file);
    return chars;
}

bool RunExtraCode(v8::Isolate* isolate, v8::Local<v8::Context> context,
    const char* utf8_source, const char* name)
{
    v8::base::ElapsedTimer timer;
    timer.Start();
    v8::Context::Scope context_scope(context);
    v8::TryCatch try_catch(isolate);
    v8::Local<v8::String> source_string;
    if (!v8::String::NewFromUtf8(isolate, utf8_source, v8::NewStringType::kNormal)
             .ToLocal(&source_string)) {
        return false;
    }
    v8::Local<v8::String> resource_name = v8::String::NewFromUtf8(isolate, name, v8::NewStringType::kNormal)
                                              .ToLocalChecked();
    v8::ScriptOrigin origin(resource_name);
    v8::ScriptCompiler::Source source(source_string, origin);
    v8::Local<v8::Script> script;
    if (!v8::ScriptCompiler::Compile(context, &source).ToLocal(&script))
        return false;
    if (script->Run(context).IsEmpty())
        return false;
    if (i::FLAG_profile_deserialization) {
        i::PrintF("Executing custom snapshot script %s took %0.3f ms\n", name,
            timer.Elapsed().InMillisecondsF());
    }
    timer.Stop();
    CHECK(!try_catch.HasCaught());
    return true;
}

v8::StartupData CreateSnapshotDataBlob(v8::SnapshotCreator* snapshot_creator,
    const char* script_source = nullptr)
{
    // Create a new isolate and a new context from scratch, optionally run
    // a script to embed, and serialize to create a snapshot blob.
    v8::StartupData result = { nullptr, 0 };
    v8::base::ElapsedTimer timer;
    timer.Start();
    {
        v8::Isolate* isolate = snapshot_creator->GetIsolate();
        {
            v8::HandleScope scope(isolate);
            v8::Local<v8::Context> context = v8::Context::New(isolate);
            if (script_source != nullptr && !RunExtraCode(isolate, context, script_source, "<embedded>")) {
                return result;
            }
            snapshot_creator->SetDefaultContext(context);
        }
        result = snapshot_creator->CreateBlob(
            v8::SnapshotCreator::FunctionCodeHandling::kClear);
    }

    if (i::FLAG_profile_deserialization) {
        i::PrintF("Creating snapshot took %0.3f ms\n",
            timer.Elapsed().InMillisecondsF());
    }
    timer.Stop();
    return result;
}

v8::StartupData WarmUpSnapshotDataBlob(v8::SnapshotCreator* snapshot_creator,
    const char* warmup_source)
{
    CHECK_NOT_NULL(warmup_source);
    // Use following steps to create a warmed up snapshot blob from a cold one:
    //  - Create a new isolate from the cold snapshot.
    //  - Create a new context to run the warmup script. This will trigger
    //    compilation of executed functions.
    //  - Create a new context. This context will be unpolluted.
    //  - Serialize the isolate and the second context into a new snapshot blob.
    v8::StartupData result = { nullptr, 0 };
    v8::base::ElapsedTimer timer;
    timer.Start();
    {
        v8::Isolate* isolate = snapshot_creator->GetIsolate();
        {
            v8::HandleScope scope(isolate);
            v8::Local<v8::Context> context = v8::Context::New(isolate);
            if (!RunExtraCode(isolate, context, warmup_source, "<warm-up>")) {
                return result;
            }
        }
        {
            v8::HandleScope handle_scope(isolate);
            isolate->ContextDisposedNotification(false);
            v8::Local<v8::Context> context = v8::Context::New(isolate);
            snapshot_creator->SetDefaultContext(context);
        }
        result = snapshot_creator->CreateBlob(
            v8::SnapshotCreator::FunctionCodeHandling::kKeep);
    }

    if (i::FLAG_profile_deserialization) {
        i::PrintF("Warming up snapshot took %0.3f ms\n",
            timer.Elapsed().InMillisecondsF());
    }
    timer.Stop();
    return result;
}

void WriteEmbeddedFile(i::EmbeddedFileWriter* writer)
{
    i::EmbeddedData embedded_blob = i::EmbeddedData::FromBlob();
    writer->WriteEmbedded(&embedded_blob);
}

using CounterMap = std::map<std::string, int>;
CounterMap* counter_map_ = nullptr;

void MaybeSetCounterFunction(v8::Isolate* isolate)
{
    // If --native-code-counters is on then we enable all counters to make
    // sure we generate code to increment them from the snapshot.
    //
    // Note: For the sake of the mksnapshot, the counter function must only
    // return distinct addresses for each counter s.t. the serializer can properly
    // distinguish between them. In theory it should be okay to just return an
    // incremented int value each time this function is called, but we play it
    // safe and return a real distinct memory location tied to every counter name.
    if (i::FLAG_native_code_counters) {
        counter_map_ = new CounterMap();
        isolate->SetCounterFunction([](const char* name) -> int* {
            auto map_entry = counter_map_->find(name);
            if (map_entry == counter_map_->end()) {
                counter_map_->emplace(name, 0);
            }
            return &counter_map_->at(name);
        });
    }
}

} // namespace

int main(int argc, char** argv)
{
    v8::base::EnsureConsoleOutput();

    // Make mksnapshot runs predictable to create reproducible snapshots.
    i::FLAG_predictable = true;

    // Print the usage if an error occurs when parsing the command line
    // flags or if the help flag is set.
    int result = i::FlagList::SetFlagsFromCommandLine(&argc, argv, true);
    if (result > 0 || (argc > 3) || i::FLAG_help) {
        ::printf("Usage: %s --startup_src=... --startup_blob=... [extras]\n",
            argv[0]);
        i::FlagList::PrintHelp();
        return !i::FLAG_help;
    }

    i::CpuFeatures::Probe(true);
    v8::V8::InitializeICUDefaultLocation(argv[0]);
    std::unique_ptr<v8::Platform> platform = v8::platform::NewDefaultPlatform();
    v8::V8::InitializePlatform(platform.get());
    v8::V8::Initialize();

    {
        SnapshotFileWriter snapshot_writer;
        snapshot_writer.SetSnapshotFile(i::FLAG_startup_src);
        snapshot_writer.SetStartupBlobFile(i::FLAG_startup_blob);

        i::EmbeddedFileWriter embedded_writer;
        embedded_writer.SetEmbeddedFile(i::FLAG_embedded_src);
        if (i::FLAG_embedded_variant != nullptr) {
            embedded_writer.SetEmbeddedVariant(i::FLAG_embedded_variant);
        }

        std::unique_ptr<char> embed_script(
            GetExtraCode(argc >= 2 ? argv[1] : nullptr, "embedding"));
        std::unique_ptr<char> warmup_script(
            GetExtraCode(argc >= 3 ? argv[2] : nullptr, "warm up"));

        i::DisableEmbeddedBlobRefcounting();
        v8::StartupData blob;
        {
            v8::Isolate* isolate = v8::Isolate::Allocate();

            MaybeSetCounterFunction(isolate);

            if (i::FLAG_embedded_builtins) {
                // Set code range such that relative jumps for builtins to
                // builtin calls in the snapshot are possible.
                i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(isolate);
                size_t code_range_size = i::kMaximalCodeRangeSize == 0
                    ? i::kMaxPCRelativeCodeRangeInMB
                    : std::min(i::kMaximalCodeRangeSize / i::MB,
                        i::kMaxPCRelativeCodeRangeInMB);
                i_isolate->heap()->ConfigureHeap(0, 0, code_range_size);
                // The isolate contains data from builtin compilation that needs
                // to be written out if builtins are embedded.
                i_isolate->RegisterEmbeddedFileWriter(&embedded_writer);
            }
            v8::SnapshotCreator snapshot_creator(isolate);
            if (i::FLAG_embedded_builtins) {
                WriteEmbeddedFile(&embedded_writer);
            }
            blob = CreateSnapshotDataBlob(&snapshot_creator, embed_script.get());
        }

        if (warmup_script) {
            CHECK(blob.raw_size > 0 && blob.data != nullptr);
            v8::StartupData cold = blob;
            v8::SnapshotCreator snapshot_creator(nullptr, &cold);
            blob = WarmUpSnapshotDataBlob(&snapshot_creator, warmup_script.get());
            delete[] cold.data;
        }

        delete counter_map_;

        CHECK(blob.data);
        snapshot_writer.WriteSnapshot(blob);
        delete[] blob.data;
    }
    i::FreeCurrentEmbeddedBlob();

    v8::V8::Dispose();
    v8::V8::ShutdownPlatform();
    return 0;
}
